11 



tioned by certain metabolic processes, the rate of which are further 

 conditioned by the presence of certain substances, as enzymes (from 

 Hver, etc.), and internal secretions (from thyroid, testes, adrenals, 

 etc.). The influence of certain physiological conditions or processes 

 is thus well known to affect the behavior of animals. The changes 

 of instinct through the removal of the testes or ovaries, may be cited 

 as examples of this influence. An animal whose metabolic processes 

 have reached a certain stage is said to be satiated ; later it is in the con- 

 dition of incipient hunger; and still later, in the physiological condi- 

 tion of intense hunger. These internal changes cause the animal to 

 react very differently to any food which is in its immediate vicinity. 

 These changes in physiological conditions are strictly comparable to 

 the change which an animal passes through in its ontogeny; to the life 

 cycle of an insect, for example, in wdiich the physiological conditions 

 and behavior of a caterpillar are very different from those of the pupa 

 and of the adult or moth. One of the higher animals, a dog, for in- 

 stance, will undergo internal changes which will completely alter its 

 responses at the sight of an old rival or enemy. Such considerations 

 as those just cited show^ clearly that extensive internal physiological 

 changes take place in animals, and that while some of them are very 

 gradual others are exceedingly rapid. These internal conditions or 

 changes have been well characterized by Jennings ('06:289) as fol- 

 lows : "The 'physiological state' is evidently to be looked upon as a 

 dynamic condition, not as a static one. It is a certain way in which 

 bodily processes are taking place, and tends directly to the production 

 of some change. In this respect the 'law of dynamogenesis,' pro- 

 pounded for ideas of movement in man, applies to it directly (Bald- 

 win, '97: 167) ; ideas must indeed be considered so far as their objec- 

 tive accompaniments are concerned, as certain physiological states 

 in higher organisms. The changes toward which the physiological 

 state tends are of two kinds. First, the physiological state (like the 

 idea) tends to produce movement. This movement often results in 

 such a change of conditions as destroys the physiological state under 

 consideration. But in case it does not, then the second tendency of the 

 physiological state shows itself. It tends to resolve itself into another 

 and different state." 



I may thus summarize the relation of metabolic processes to 

 physiological conditions and processes of behavior by the following 

 table. 



